SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548f08db3e3d137be7c7a8d80b1f8219d56291124cb210a0d873f427b8908203' 
  AND token = 'P/wOl9qTtwMnti72vu10Mwe3eLif+g6fSg7T8ETtrfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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