SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dab31125b4befea252b397980db88bec994d26e7ddf866142098dfce322b2db' 
  AND token = 'cZIxS7bWjyMJW1dDsFll711ZFHQdfJhFBKs0Id2QtBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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