SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '552cb8a23b285ca142d8073ecc252bc22d82c3a761a54078b676326305288502' 
  AND token = 'v8fFc3u2tx8LjG9ub8kCSidvzKl6gVFEhJjUE1V85iI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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