SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f31a86af0e0355a1e8f0d54a03474aa9b98be83fa44703389b30774081ce2bc' 
  AND token = 'roseUjFhPQD99ztmw8TCF77b+YGRWzrh/22JZqG8XGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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