SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '838d2caa19671c7734fbdd8c361436f65ab7e3fee9f6c7403a17143f70d86717' 
  AND token = 'tew9/NPLlOUzuY2H2icBPWL9a/SWJxbIJEx/8FEPflQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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