SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '986d93ee94217028c8eaffdb63f44ea2f50a5030f823a0ce17a56172ad5e55bd' 
  AND token = '+goREu4OWwL2crfv9ZiXC5ED6NkRlTCVNwQ8/CQwokM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00075

JSON explain

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