SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b940b5845df09bfc2f71c4804020a373813438df71fcf49b9a9cf7d2355b9589' 
  AND token = 'ND5tqBmlUuIBaTuwnaLFFA51NSTMniRA313KVQSjCrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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