SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '536ce87f841a5fde9885804f62cb85140bdb4793b90c7fb099856d4afc3c13dc' 
  AND token = 'fpnJT42CgWqWfKYB6UvEIOr/kb3m9yTxPRgLN+jxy0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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