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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b05353a39f342e7437739681fde3481a97c8ddf1a2eca83521c2126c6978c6a8' 
  AND token = 'bf6dUd7lOahtkp8YmU5Wv7LJfoMTU8UrtR1i+thWjTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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