SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6608ab097b81bd6226dbf05c311149c77060858fdd0a3cd360490c011c7183c' 
  AND token = 'DPJGJmqw1AlTS8cEa9ke+6FJDosYy3KzpeJpwV7SEWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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