SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf4a500b40146121819285788bf50e279184ed5d62f68f0b44d39a47d5e6a1db' 
  AND token = 'ZIOnXcCdCzVUA5THSKPLvSP45OVJq5J+lBhUeCBXJ+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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