SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b48811cb6e6daf1e014e1e2e8e3244e067d47f9b910d38dbecfbb7c7385c2525' 
  AND token = 'YYRJjNVHkHgYLQO3Y/1vwTOL9cYbXCAYQIRYLZQjjGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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