SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35a490602dcae8b6bde7c30b87ca2b44b5da9022e3cbfe7992c63598ff8a50e8' 
  AND token = 'vUmBhZWOanWRTCpDLvwVQGnhRsz42wswBOeg2nGVNmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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