SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '639bcc6cfa64e695c9888fe3363e2692836c41fb57dddf99845b4f44a3dcb8fb' 
  AND token = '49WYf08TfnW1uKk25nltEMoQk1oDhTApQfT252nsRO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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