SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '509495951dddceabf9fabafa52562f11c20031c7a837d0f6b955a730189eac56' 
  AND token = 'qdfMWN3ZKX7a/TasOvZqS2QVL6bge5Qi+4YYWmnVrCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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