SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c85ae0d6c651cd8519d1825cfb82978445611f535de6e117d497b89f77afdad' 
  AND token = 'm83mZYW0lQeIYtFPurfjo+xV1LojLY+Ht3z0JAjCbMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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