SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ffaf3347549cdd024bac9d3de2b5fb71c895fb474b965632b8fde2083e8f669' 
  AND token = '5EGybFunucT4JrE1BNNIrmGM7AOfMuyJumXi4M6FDwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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