SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2106804c682339a1fac7485ad60dc08522688d83a6b766d936cbefee44761f04' 
  AND token = 'mvE2uhVC+Iyr6UjHihQ1wgzLz/dWXBhH7vjV02pTxxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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