SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c7793d167bb144581cc86dcb5db56d5710a943f1a7f817cf6105f3da261aceb' 
  AND token = 'VyKzHfmsmpTGqTuyHg0u1+VElwLbAdb/2fCy5U4Kz3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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