SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '296796600028baf848c1542d114fef22398633c2c05f177d7cd77a4b6eee85d0' 
  AND token = 'JWBZ6av20iVO+KdnRv692H/a2fQ3UnF3L3ZGt5JG7L4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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