SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0df0207d55f8bc78d0cec3b811bbdad7399bc14f6665eb54f56a231fe92a0f82' 
  AND token = 'NMlcwU7ExawDIAiaZ+I1pFVaAyYqkZPdFohsKWsGKHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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