SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a88c2e04a1a86f1c156810b043009d7dee88f3197eef6e7594878fa01b19c189' 
  AND token = 'Clx16lftt91T0mgdrszChwN7UOc13Oq8smL8xSTMDdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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