SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dece5b2b2c1203292d2914ee9ba9b848475812f83f5b0f4e47f3e2c20a92100e' 
  AND token = '9k8xVdPhyewhGCWS4p/Us5fiIouTnd0TPG6NavdCE2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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