SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ef3b38d25e224026bbf58e66884c1f031d9d9c47986fa40e91ff327193e5f54' 
  AND token = '/YJG0psKpNMF9m2dnXPw2mKjCGev5z29BDA0uSVnprw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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