SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '591c0ee6772060337da086d92d7c31fb867a5154a3205b2215f674a151208fe1' 
  AND token = '+g1yG1JIQa1+9xGij/WAyMcpnKqVmBIPkfxPhRnP6bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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