SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '355f9e7bad77567286576324bc446a160d6fd787739e1988358ac2af1fc8eb9d' 
  AND token = '0Kds6Zs1X/SpXfUFQ19CWJBMzynBJe3eVJRlOGxZEos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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