SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4765a1935369e3c656f002761f8c283486ddb26a0ec42758c9d471a59e84dba6' 
  AND token = 'nxtWBRhuo176e8kMu4HspI5SMtPNFAgTL5ynBjkm9HI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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