SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f928a11de219e874ed6563be3cf54616905018230b2eea8de377bee0b19d3ea0' 
  AND token = 'llD1ritcRt7l8DMqix4+1IhRucb5yk2f903PoFWuiLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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