SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4313f9bf0daaa90b2a7771f114eaf4f29d448d16d01123f618b2468f508656' 
  AND token = 'JRmHz7ErdnKrn4aR6+sK1ENRzLNkRSteEsh0p4IxloI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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