SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f0b4b5fc4191e6e0b8a830bef9e95d37999ef2a999aba96689d65551856291d' 
  AND token = 'YcIQUXlnvs6EuYKnxsTlS8KOyFwPmmT7IOPXhvZ+ZWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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