SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ec7ccc1f697c2249aaf86b2dc246277e047b8a249f205597a5ac336d055d75a' 
  AND token = '+h61VBShM3wCmh3ns5/s9J5gKf3glQI+NY2jfawAOMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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