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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1917ac665531f3b91cbc7977e53caccdd2f6b4d3b51dc4a323a32d9ae0c51a66' 
  AND token = 'YfcdYsQDU8UCZUr6WpWduN4oFdXlB0iqcaCWpXwtsOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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