SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'db6f1a8466cb6aad3fb0a12e6f4f7e4911844f9c94659b3533e78a35881064d2' 
  AND token = 'lzzrickGNejztkGKxVDgvftI6XoCEaPueyJSzXz0S4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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