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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9d271b14e27cc5a3a07cf4ea0c2bf00f9e91cf91a8fab3cccac37d3ee276298' 
  AND token = 'vsmwQqEYYpbuRuY8utH8tUpAdvXQzUZLr4PpP9TeZF8=' 
  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"
    }
  }
}