SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90155f295f861a8ee144b916a434ed5434fbe4b0030769ccce4f2da83863c289' 
  AND token = 's6KsCUyWV00Y0vAQjBh+KI3D7KVjtNpuDFI0EMyuFiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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