SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15f8472bb8200da072cae6a511091fbdb6c0b830e508591fd4b76ade4dfcc132' 
  AND token = 'mssoRPizjAkJJZtVyGYtGV/uMbDZnCi9urXOlvEQ/cA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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