SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ec8258fe228d8882f990444edee3897a0afa2d45c4484bde818cd1a1d87a755' 
  AND token = 'dnLL8ebhnjMCHtWeWTZyuwq1BbP2sel5QzEiDlEfvzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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