SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e06b5013f6542354ef4e146fde74bcfdeffc4e2e8c5921718f0e534becc3fe' 
  AND token = 'pqLMUJMIA4k3pcVMaZxWTEZUjxEEBmo3jZmipEXjvEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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