SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b23a55fc6fe475e9ab95da958abe254c2e948fecacd5b7b2ecc324f758e2ce4b' 
  AND token = 'dKF8zR8SCTUtWofqFV1V/fgv7+6gGlBT9WvvQWuJWqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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