SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '506440aaed84c0ef78ccbedebecf9eaa77fb2487383be385f08980b07f163aec' 
  AND token = '0CYcBMANDeR+8B7RK6SoKkZbuPMKOPWb5iqzgONzffM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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