SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b56cf4aceb9522ad30559201f588049a28bef8900a38b6a0df4cc9a4d8abd966' 
  AND token = 'm63pzavllJUupZXDUWKV9TcduofvpMOm00i5euwi4b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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