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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75dfb7dd52cd6be06fd884bd6a2bf380e250961cb3e0dc97cc048a252b4493f9' 
  AND token = 'YdXSLgcPZMAq1qPz+JsmDY3C5OQpsO1LTIv1DHIAaOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}