SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f85a134e77785062d971c645cdff7999d1840bf3452c1003027aa3e89204fffd' 
  AND token = 'p34uJ3zJrCSRC+84kJTC98kKSlNyCnZV6rumI6nU73A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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