SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d38a129e64952fab83e75cf61203947a5cdb88e295b510594caa322b33a25bb' 
  AND token = 'IiixlRhyJRSU+k4CCvE5pqwNJcDhvsUzprnTnIe/8JU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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