SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdc5376d238a1d3513d8da642ea093e41bfddaa6917e32bd014afca29ee3fd8f' 
  AND token = 'KSPFhplD6624jHF271Iun1MwbXzGVT+d1l5hngGRBTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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