SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99f6693aaac0c68b17652654a95027bf7f8e2b460c12088bd467a38132d46ced' 
  AND token = 'dVn7YMjkHJbjSrTOtiY2UEThdrNtKzt4FdRfkiRNZAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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