SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6789a61528e0246e60c19342145cf721c5522fd662238ca078bea1d66a71efc1' 
  AND token = 'QwgvzBWiRYMJCg4JFvFGdGtX/ZWOAv52cWsVrlSGHb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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