SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f8f7c3a09634f7f52822385285a3251ea4df2341558d830259206bd5bbaffda' 
  AND token = 'Qh855ZBAG1nBw0Whc/ttbD5fuApc/t242rid7ejfzNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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