SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e62d70e3690394ef65da18cfce80b1552d7bad4399846b65e6086b8b4bcde331' 
  AND token = 'VlNaRkC1GSdawRrRbzKbsVPaCp3VWnzYH83ie1d/iEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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