SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5388e02cab20274d3ff5dd6b214af4694f386b3939dbfa20c7c2105173194f29' 
  AND token = 'bSzt050JTYmRFvAVghmjyj8eIM+plMypgOqcIQKerfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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