SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9e545d859f2e97da0797f4f48f40b80e0ad2e53fde98c1283c2821486b13337' 
  AND token = 'QMVqay6uFCw1u+rNsToPwz0KscqFXZoO+fVBIeF/HJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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