SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3475c158f562fa7611cba0602e821e74208013d074abb8a5efb1f068275009d4' 
  AND token = 'pi584ttPtKfrSK88Y4YfUxwcsVFkZ+bflyFzFIr2iv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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