SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38970410716d5bf11306db786399a9e3b3eda68fd7cdc9ca2a631648bc41fca4' 
  AND token = 'eI7w7c/X0LcMMQk8Ok+GiHIKSYNSNQfeLK562IuuHqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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