SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89a3001517ac4d96e7f33da7faf6d591c8734009e12ffb8289b8c2e792ab476a' 
  AND token = 'n2GfFOjahhekXGUCr9tiXZTf0S+XbeSt/upx6TUPDPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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