SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a591d1414f97ba7d54603e82dcf0e7b2bdba6def68d64f148932528451fc391a' 
  AND token = 'I720yzIZ1Ula9DzXZRB56pD5jG7SGv6AhmYQsjO5vuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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