SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5122d76c8ff653bfbe8282ec7333c77bd09df6d21d34442eb23acdf77e05039f' 
  AND token = 'UslQ/pQNYAZYJHP/WYV6v2vqDQKzZexPsVbiZZ+3N8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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