SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '875938a3987ce677fbe3e36a69b8075dd59b4af0198394d85d1f839a569f4719' 
  AND token = '5jCPljAAxgIFPJyJRifPdEVBLCNJU/yFOgGm23qzvGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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