SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '775a78bb53056d45f31c172d1919d6d5100846ba04c714212915e5759aec6423' 
  AND token = 'OxEnoLfn+jwhpnbbGLyhmHPJQhUpopKgtkXgNC07tAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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