SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad71ca6de66e9162a712a406765ed99fe4332717bac6ef73771a07abd3f63020' 
  AND token = 'r8D5dO95tDDMrcWJi6pze72xd/0hfL3+SQHQZKleUFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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