SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4eb76f3f44c38ef76495fd1107b4d3f063114d6a2815291c043975bb0dc3bb0' 
  AND token = '9gxdkkJSjkO+hq4eS865CJ+91s/8fcjWfEFP0UR/zxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}