SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b378c99a7d51c04d55e2ef90ce78bbd32bf808bf787190fcef65a62ea6f81ca9' 
  AND token = '4kDCsROS7crauTedHsXFGjCi+uzDOxiqnEQOiwM5eFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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