SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a5f2b1267c70c97c03bbf8ff0146caff13472c1f5d5a75a1db60ae3939d1b95' 
  AND token = 'BFH6c7wTyLXZ6+OTMz8A6zYYPAv/+E3o9DFpGmGVNjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}