SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42b80005f8bb52e796ee57eaa467e6a46ef37c7e69241fac961689055d637de0' 
  AND token = 'uBj9Vg/M7v2bo3/+JXjYBOXo7vIpsCIFIzUpkMIks1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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