SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b810ee808cc02d288d30cbdab86ae46243b5e83edefd9441707874544e52ad25' 
  AND token = '2eNzEqOHV/a4fdG5xZqCKQIHtn2LWyhGp+VODm3nOjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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