SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90ab48640f1c960cbe0ad802c052f92565113be0258422da4564fb7c9b4e1900' 
  AND token = 'k2qkW2ngUd3cgQvT3tW2O6SWc0EbcxXxylefXyy18gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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