SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c6a3e4d82b42628c22407f675a35e320b8529f8afc090bf5c00bcd4f3fc5538' 
  AND token = 'xVOEiA/cCYkqtudVsAySCJdFjEUJYQ0sCaWTIxHzQzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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