SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c716754cceab10ecb0faf48a11fa473a26e801179387444dd14ecce560084eb3' 
  AND token = 'U3QKWvB7xrwFC62ONcDFsPKUEjnyKo/Wy59bXXb3oo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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