SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9a2d603d76a5f89c01501415257d574c5d1c0fadf10d32eea93a0bcf34b2193' 
  AND token = 'GutxLXquT7iMypMzcKoTNpATZtwgMr7WjYJFydwXidk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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