SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3b8bfde8d0372ddae1d77014ec91de528f113b020dd746caad5a73b04d2f661' 
  AND token = 'UTOFkK1D7RsTIaRpEbHQaFgoBFAVsDi5BirLMPPLpgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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