SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '271fa38b2293f17a94a4fc955c83f3a6a1cf99c5bb3427f1bd5537db10c6d4aa' 
  AND token = '0EjNCvdR6BvqkLibLI4JoHFc3KGv+rFrXRyckrcHi2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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