SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4288c2f02b529721616c1b447666b856e2c49db5b302dbef7834d29c65294d95' 
  AND token = 'dblZK+GN+jqfX6JVUsPVIjAXfaKO+LebzWlhSEOPUls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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