SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '891eede2e5aa7d10b956d2d048144fa429f83662714dc8253d9a83f21afd8c34' 
  AND token = 'Hm5qZLsO+6y1hgvQIW2cM/YPLUkEoMIllr4016/SKBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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