SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc0e915e4515c3f04d1c5eadb6370b3ca2fec8679095a513bdb2297004443972' 
  AND token = 'I45yORDnobH6qBFtadYOk5uNIuxuZwP9egbef8/+68M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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