SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '867727fd50405c7ac0c927dad6891c5141a71602d0602b7838e9d73155f5781a' 
  AND token = '255JXEEr/AN2osUYZ/EYp0/KyMubahjmX5KX7FKEYE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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