SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a31721ee642a5d5771a905ae2e03fe40ee756202dc9221363c784641ef1e24d' 
  AND token = 'xwwQ6iWyqxuu7SZBu6qZjWYruql+hyK7zxQDcIpMjS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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