SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98eb44ca29d633655bdb06c4344df90c5ea73d60d97dbd367e050ad1c3bfcb59' 
  AND token = 'BhcYvKuxQmMnplvT6eRlcdxnKbS2kSpcVdwvqtLwzzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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