SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd851ac38f20a80adc243a76d3edf78d07ba038906c2d2286ac0d5c2e6acbcc67' 
  AND token = 'bI8Wi0KEnh22IlUdSKQDsKJ6vNWC/xaajjzXmvnvsEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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