SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5df709c8532a07917fe48ca49df6cae424d69e284d91fbc65108a6dd4f3c7a13' 
  AND token = 'Kr3nFga8y7ySYai5alTntljeukKulsudQiPvSf1zRsM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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