SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31a0ad526240a63f05e2a7a328bcccc36f467e19bea4d7bd8542977fa5552abc' 
  AND token = 'do3xCV/8jDPzd+lKmrEYMYLZv6yd2Pwwv338FpNqsZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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