SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '277dc0dcbf18ea588163ce01b60eaed2c112c25cbfdb21add0311863620b7860' 
  AND token = 'FeRhiOCVj2gnItlpyDu1ot+6wbgIk8yIF4iKQcua424=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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