SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6b69a5a44276544f6c99674c49ca535721dd1b58458b6f8e13b1277d3822f2a' 
  AND token = 'noKBrYZs1dUGnTypNVUw6m6uZnFF7+1Oqg4NNCGx3Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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