SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3447c04967566099064549bf90a52ab0826c9935155e044ee73681d5ae53b28' 
  AND token = 'JS9nMqdEN0ZwvgouGvdr0RRu/PKkmenxkAXMjTMEfBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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