SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a5b838559c85e632ee3fb9d006f516eec75549cf147d77d76739d74c9d979f4' 
  AND token = 'a/TQ8PR2XZbIClFhdHPEBUGkSAmsPztUUVH8SGjK+2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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